/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.table.runtime.operators.sort;

import org.apache.flink.core.memory.MemorySegment;
import org.apache.flink.table.runtime.util.MemorySegmentPool;

import java.util.List;

/**
 * MemorySegment pool of a MemorySegment list.
 */
public class ListMemorySegmentPool implements MemorySegmentPool {

	private final List<MemorySegment> segments;
	private final int pageSize;

	public ListMemorySegmentPool(List<MemorySegment> memorySegments) {
		this.segments = memorySegments;
		this.pageSize = segments.get(0).size();
	}

	@Override
	public MemorySegment nextSegment() {
		if (this.segments.size() > 0) {
			return this.segments.remove(this.segments.size() - 1);
		} else {
			return null;
		}
	}

	@Override
	public int pageSize() {
		return pageSize;
	}

	@Override
	public void returnAll(List<MemorySegment> memory) {
		segments.addAll(memory);
	}

	@Override
	public int freePages() {
		return segments.size();
	}

	public void clear() {
		segments.clear();
	}
}
